1. Field of the Invention
The present invention relates to a technology for controlling the localization position of a sound image by providing a delay-time difference between outputs of speakers in an audio system.
2. Description of the Related Art
An example of known technology for controlling the position of sound image localization by providing a delay-time difference between outputs of speakers in an audio system is described in Japanese Unexamined Patent Application Publication No. 10-248098. An acoustic processing system disclosed therein has delay units provided for respective speakers for delaying audio signals to be sent to the speakers. Upon receiving the designation of an audio-sound listening position from a user, the acoustic processing system sets delay times for the respective delay units so that the sound image is localized ahead of the received listening position, in accordance with the relationship between a preset listening position and delay times for audio signals sent to the respective speakers.
According to the known technology, the delay times for the audio signals to be sent to the respective speakers are controlled based on a listening position designated by the user and the relationship between the pre-set listening position and the delay times of audio signals to be sent to the respective speakers. However, with such control, in some cases, the sound image cannot be correctly localized to a position desired by the user, depending on the in-vehicle environment. In such a case, the user needs to perform complicated work, i.e., checking the localization position of audio sound produced by the speakers while gradually varying the designated listening position in a trial and error manner, until the output audio sound is localized to a desired position.